Ultrasound imaging apparatus and method for displaying ultrasound image

ABSTRACT

An imaging part acquires a plurality of ultrasound image data by sequentially imaging the subject with ultrasound waves. A display controller causes a display to display, side by side, a plurality of ultrasound images based on the plurality of ultrasound image data acquired by the imaging part. 
     Moreover, the display controller causes the display to display measurement markers for obtaining quantitative information of tissues shown in the ultrasound images in a state superimposed in relatively the same positions on the plurality of ultrasound images.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ultrasound imaging apparatus thattransmits ultrasound waves to the subject, generates an ultrasound imagebased on reflected waves from the subject and displays the ultrasoundimage, and also relates to a method for displaying an ultrasound image.In particular, the present invention relates to an ultrasound imagingapparatus that obtains quantitative information of tissue shown in anultrasound image, and also relates to a method for displaying anultrasound image.

2. Description of the Related Art

An ultrasound imaging apparatus transmits ultrasound waves to thesubject and generates ultrasound image data representing the morphologyof tissue within the subject based on reflected waves from the subject.An ultrasound imaging apparatus according to a conventional art has afunction of measuring the size of tissue such as a lesion site and organshown in an ultrasound image. For example, the ultrasound imagingapparatus is provided with a function of measuring the distance betweentwo points in tissue like a lesion site, a function of measuring theperimeter of tissue, a function of measuring the area of tissue, etc.

In the abovementioned measurement functions, a measurement marker calleda measurement caliper is displayed on an ultrasound image. Thismeasurement caliper can be moved on a screen with an input device suchas a trackball. An operator fits the position of the measurement caliperto the position of a site to be measured shown in an ultrasound image.The ultrasound imaging apparatus obtains a quantitative value bymeasuring the size of tissue designated with the measurement caliper.For example, it is possible to designate two points on an ultrasoundimage with the measurement caliper to measure the distance between thedesignated two points.

Further, a plurality of ultrasound images may be displayed side by sideto measure the size of a measurement target shown in each of theultrasound images. For example, in the case of simultaneous display oftwo ultrasound images, conventionally, a measurement caliper isdisplayed on one of the ultrasound images, and the operator moves themeasurement caliper to the position of a measurement target to measurethe size of the measurement target shown in the one ultrasound image.Next, the measurement caliper is displayed on the other ultrasoundimage, and the operator moves the measurement caliper to the position ofa measurement target to measure the size of the measurement target shownin the other ultrasound image. Thus, conventionally, the measurement isexecuted by individually operating the measurement caliper in each ofthe ultrasound images and designating a measurement target shown in eachof the ultrasound images.

Further, there is a known method of displaying a B-mode image capturedin the B-mode and an M-mode image captured in the M-mode side by side toobtain the quantitative value of a measurement target shown in theB-mode image in a case that a measurement caliper is on the B-mode imagewhereas obtain the quantitative value of a measurement target shown inthe M-mode in a case that the measurement caliper is on the M-mode image(Japanese Examined Patent Publication No. 62-4978).

Further, there is a method of simultaneously displaying two ultrasoundimages, and displaying a cursor in a designated position on one of theultrasound images, whereas displaying another cursor on the otherultrasound image in a position corresponding to the designated positionon the one ultrasound image (Japanese Unexamined Patent Publication No.11-221216).

However, in the case of simultaneously displaying a plurality ofultrasound images, it is difficult for the operator to grasp thepositional relation between the images. Therefore, it is difficult forthe operator to observe a plurality of ultrasound images, move ameasurement caliper to positions corresponding to each other on theplurality of ultrasound images, and measure the size of measurementtargets.

Further, by injecting a contrast agent into the subject and imaging, itis possible to generate a contrast enhanced image in which a site withthe contrast agent injected is enhanced. For example, by injecting acontrast agent into the subject and imaging by Contrast Harmonic Imaging(CHI), it is possible to generate a harmonic image based on harmonicwaves. Then, a body tissue image representing the morphology of bodytissue and a contrast enhanced image obtained in contrast imaging aresimultaneously displayed. A body tissue image shows, for example, themorphology of tumor. Moreover, a contrast enhanced image shows a sitewith microbubbles of a contrast agent injected is enhanced. Even in thecase of thus simultaneously displaying a body tissue image and acontrast enhanced image, it is difficult for the operator to grasp thepositional relation between the tumor shown in the body tissue image andthe site with the contrast agent injected shown in the contrast enhancedimage. Therefore, it is difficult for the operator to determine whetheror not the contrast agent is injected in the tumor based on the bodytissue image and the contrast enhanced image. Besides, a method ofdisplaying the contrast enhanced image and the body tissue image in thesuperimposed state is known, but there is a problem that contrastresolution (gradation) decreases because the two images are superimposedon each other.

Additionally, when the contrast enhanced image is superimposed on thebody tissue image, the body tissue image is hidden behind the contrastenhanced image. Therefore, it is difficult for the operator to grasp theaccurate positional relation between the site with the contrast enhancedimage injected and the tissue shown in the body tissue image.

As described above, it is difficult for the operator to grasp the imagepositional relation between the body tissue image and the contrastenhanced image. Therefore, it is difficult to move the measurementcaliper to the corresponding positions on the body tissue image and thecontrast enhanced image to designate the measurement targets.

Further, the abovementioned method described in Japanese Examined PatentPublication No. 62-4978 is a method of executing the measurement on theimage with the measurement caliper displayed of the B-mode image and theM-mode image. Therefore, it is difficult for the operator to execute themeasurement by moving the measurement caliper to the correspondingpositions on the plurality of ultrasound images. Besides, in the methoddescribed in Japanese Unexamined Patent Publication No. 11-221216, themeasurement using the measurement caliper is not executed. Therefore, itis difficult to execute the measurement in the corresponding positionson the plurality of ultrasound images.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an ultrasound imagingapparatus that can, in the case of simultaneously displaying a pluralityof ultrasound images, specify positions corresponding to each other onthe plurality of ultrasound images and measure measurement targets inthe corresponding positions, and also provide a method for displaying anultrasound image.

A first aspect of the present invention is an ultrasound imagingapparatus, comprising: an imaging part configured to acquire a pluralityof ultrasound image data by sequentially imaging a subject withultrasound waves; and a display controller configured to cause a displayto display, side by side, a plurality of ultrasound images based on theplurality of ultrasound image data acquired by the imaging part and alsocause the display to display measurement markers for obtainingquantitative information of tissues shown in the ultrasound images in astate superimposed on the plurality of ultrasound images in relativelysame positions.

According to the first aspect, by displaying a plurality of ultrasoundimages side by side and displaying measurement markers in a statesuperimposed on the plurality of ultrasound images in relatively samepositions, it is possible to easily specify positions corresponding toeach other on the plurality of ultrasound images. Consequently, it ispossible to measure measurement targets in the corresponding positionson the plurality of ultrasound images.

Further, a second aspect of the present invention is a method fordisplaying an ultrasound image, comprising: acquiring a plurality ofultrasound image data by sequentially imaging a subject with ultrasoundwaves; and displaying, side by side, a plurality of ultrasound imagesbased on the plurality of ultrasound image data having been acquired,and also displaying measurement markers for obtaining quantitativeinformation of tissues shown in the ultrasound images in a statesuperimposed on the plurality of ultrasound images in relatively samepositions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an ultrasound imaging apparatusaccording to an embodiment of the present invention.

FIG. 2 is a view showing an example of a screen displaying twotomographic images side by side.

FIG. 3 is a view showing an example of a screen displaying measurementmarkers on a screen displaying two tomographic images side by side.

FIG. 4 is a view showing an example of a screen displaying measurementmarkers on a screen displaying two tomographic images side by side.

FIG. 5 is a view showing an example of a screen displaying measurementmarkers on a screen displaying two tomographic images side by side.

FIG. 6 is a view showing an example of a screen displaying measurementmarkers on a screen displaying two tomographic images side by side.

FIG. 7 is a view showing an example of a screen displaying measurementmarkers on a screen displaying two tomographic images side by side.

FIG. 8 is a view showing an example of a screen displaying measurementmarkers on a screen displaying two tomographic images side by side.

FIG. 9 is a view showing an example of a screen displaying measurementmarkers on a screen displaying two tomographic images side by side.

FIG. 10 is a view showing an example of a screen displaying measurementmarkers on a screen displaying two tomographic images side by side.

FIG. 11 is a view of a screen displaying an example of measurementmarkers.

FIG. 12 is a view showing an example of a screen displaying measurementmarkers on a screen displaying a tomographic image and a superimposedimage side by side.

FIG. 13 is a view showing an example of a screen displaying measurementmarkers on a vertically reversed tomographic image.

FIG. 14 is a view showing an example of a screen displaying measurementmarkers on a horizontally reversed tomographic image.

FIG. 15 is a view showing an example of a screen displaying measurementmarkers on a screen displaying a body tissue image and a harmonic imageside by side.

FIG. 16 is a view showing an example of a screen displaying measurementmarkers on a screen displaying a body tissue image and a harmonic imageside by side.

FIG. 17 is a view showing an example of a screen displaying measurementmarkers on a screen displaying two tomographic images side by side.

FIG. 18 is a view showing an example of a screen displaying measurementmarkers on a screen displaying a body tissue image and a harmonic imageside by side.

FIG. 19 is a view showing an example of a screen displaying measurementmarkers on a screen displaying a body tissue image and a harmonic imageside by side.

DETAILED DESCRIPTION OF THE EMBODIMENTS

An ultrasound imaging apparatus according to an embodiment of thepresent invention will be described with reference to FIG. 1. FIG. 1 isa block diagram showing the ultrasound imaging apparatus according tothe embodiment of the present invention.

An ultrasound imaging apparatus 1 according to this embodiment includesan ultrasound probe 2, a transceiver 3, a signal processor 4, a datastorage 5, an image generator 6, an image storage 7, a displaycontroller 8, a measuring part 10, a user interface (UI) 11, and animage processor 14.

As the ultrasound probe 2, a 1D array probe in which a plurality ofultrasound transducers are aligned in a scanning direction, or a 2Darray probe in which a plurality of ultrasound transducers aretwo-dimensionally arranged is used. Alternatively, a mechanical 1D arrayprobe capable of scanning a three-dimensional region by mechanicallyoscillating ultrasound transducers in a direction (an oscillatingdirection) orthogonal to the scanning direction may be used as theultrasound probe 2.

The transceiver 3 includes a transmitter and a receiver. The transceiver3 supplies electric signals to the ultrasound probe 2 to make theultrasound probe 2 generate ultrasound waves, and receives echo signalsreceived by the ultrasound probe 2.

The transmitter of the transceiver 3 includes a clock generationcircuit, a transmission delay circuit, and a pulsar circuit, which arenot shown in the drawings. The clock generation circuit generates clocksignals that determine the transmission timing and transmissionfrequency of ultrasound signals. The transmission delay circuit executestransmission focus by applying a delay at the time of transmission ofultrasound waves. The pulsar circuit has a corresponding number ofpulsars to the number of individual channels for the respectiveultrasound transducers. The pulsar circuit generates a driving pulse atthe delayed transmission timing and supplies an electric signal to eachof the ultrasound transducers of the ultrasound probe 2.

Further, the receiver of the transceiver 3 includes a preamplifiercircuit, an A/D conversion circuit, a reception delay circuit, and anadder circuit. The preamplifier circuit amplifies, for each receptionchannel, the echo signals outputted from the respective ultrasoundtransducers of the ultrasound probe 2. The A/D conversion circuitexecutes A/D conversion on the amplified echo signals. The receptiondelay circuit applies a delay time necessary for determining thereception directionality to the echo signals after the A/D conversion.The adder circuit adds the echo signals to which the delay time has beenapplied. By the adding, reflection components from a directioncorresponding to the reception directionality are enhanced. The signalsadded by the transceiver 3 will be referred to as “RF data.”

The signal processor 4 includes a B-mode processor. The B-mode processorvisualizes echo amplitude information and generates B-mode ultrasoundraster data from the echo signals. To be specific, the B-mode processorexecutes the Band Pass Filter process on reception signals sent from thetransceiver 3, and thereafter, detects the envelope of output signals.

Then, the B-mode processor executes the compression process bylogarithmic transformation on the detected data, thereby visualizing theecho amplitude information.

Further, the signal processor 4 may include a Doppler processor. TheDoppler processor, for example, executes quadrature detection onreception signals sent from the transceiver 3 to derive Doppler shiftfrequency components, and executes the FFT (Fast Fourier Transform)process to generate a Doppler frequency distribution representing theblood-flow rate.

Furthermore, the signal processor 4 may include a CFM (Color FlowMapping) processor. The CFM processor visualizes blood-flow information,and generates color ultrasound raster data. The blood-flow informationincludes information such as velocity, distribution and power, and theblood-flow information is obtained as binary information.

The reception signals outputted from the transceiver 3 are processed byany processor. The signal processor 4 outputs the ultrasound raster dataafter the signal processing to the data storage 5.

The data storage 5 is composed of a storage device such as a memory anda hard disk drive. The data storage 5 stores the ultrasound raster datagenerated by the signal processor 4.

The image generator 6 reads the ultrasound raster data after the signalprocessing from the data storage 5, and converts the data after thesignal processing to coordinate data based on the spatial coordinatesystem (digital scan conversion). For example, the image generator 6executes the scan conversion process on the data after the signalprocessing outputted from the B-mode processor, thereby generatingB-mode image data representing the morphology of tissue of the inside ofthe subject. As an example, scan of a two-dimensional cross section (ascan plane) with ultrasound waves is executed by the ultrasound probe 2and the transceiver 3, and the image generator 6 generates B-mode imagedata (referred to as “tomographic image data” hereinafter) thattwo-dimensionally represents the morphology of tissue in the crosssection. The image generator 6 outputs the tomographic image data to theimage storage 7 and the display controller 8.

The image storage 7 is composed of a storage device such as a memory anda hard disk, and stores the tomographic image data generated by theimage generator 6. Moreover, the image storage 7 attaches a time wheneach of the tomographic image data has been acquired as attachedinformation to each tomographic data and stores each of the tomographicimage data.

Moreover, in the case of acquiring an ECG (Electrocardiogram) waveformof the subject by using an electrocardiograph (not shown), a controller(not shown) receives the ECG waveform from outside the ultrasoundimaging apparatus 1. Then, the not-shown controller causes the imagestorage 7 to store tomographic image data so as to be associated with atime phase received at the timing of acquisition of the tomographicimage data.

The display controller 8 receives the tomographic image data outputtedfrom the image generator 8 and causes a display 12 to display atomographic image based on the tomographic image data. Moreover, thedisplay controller 8 reads the tomographic image data stored in theimage storage 7 and causes the display 12 to display a tomographic imagebased on the tomographic image data.

The user interface (UI) 11 includes the display 12 and an operation part13. The display 12 is composed of a monitor such as a CRT and a liquidcrystal display. On the screen of the display 12, an ultrasound imagesuch as a tomographic image and a three-dimensional image is displayed.The operation part 13 is composed of a pointing device such as a mouseand a trackball, a switch, various buttons, a keyboard, or a TCS (TouchCommand Screen).

The ultrasound probe 2, the transceiver 3, the signal processor 4 andthe image generator 6 compose an example of an “imaging part” of thepresent invention. Moreover, the image storage 7 is equivalent to anexample of an “image storage” of the present invention. Moreover, thedisplay controller 8 is equivalent to an example of a “displaycontroller” of the present invention. Moreover, the operation part 13 isequivalent to an example of an “operation part” of the presentinvention.

Further, volume scan may be executed by the ultrasound probe 2 and thetransceiver 3. In this case, the signal processor 4 outputs volume dataacquired in the volume scan to the data storage 5, and the data storage5 stores the volume data. The image generator 6 reads the volume datafrom the data storage 5 and executes volume rendering on the volumedata, thereby generating three-dimensional image data thatthree-dimensionally represents tissue of the inside of the subject.Alternatively, the image generator 6 may execute the MPR (Multi PlanarReconstruction) process on the volume data, thereby generating imagedata (MPR image data) in an arbitrary cross section.

(Display of a Plurality of Images)

In this embodiment, the display controller 8 causes the display 12 tosimultaneously display, side by side, a plurality of tomographic imagesbased on a plurality of tomographic image data. For example, sequentialscan of one cross section of the subject is executed by the ultrasoundprobe 2 and the transceiver 3, and the image generator 6 sequentiallygenerates tomographic image data in the cross section. Then, when theoperator designates a desired time phase by using the operation part 13,the display controller 8 reads tomographic image data acquired in thedesignated time phase from the image storage 7 and causes the display 12to display a tomographic image based on the tomographic image data. Asan example, when the operator designates two desired time phases byusing the operation part 13, the display controller 8 reads twotomographic image data acquired in the two designated time phases fromthe image storage 7, and causes the display 12 to simultaneously displaytwo tomographic images side by side. For example, when receiving aninstruction for displaying a plurality of images from the operation part13, the display controller 8 splits the screen of the display 12 into aplurality of regions, and causes each of the split regions to display atomographic image.

As an example, in the case of displaying two images side by side, thedisplay controller 8 splits the screen of the display 12 into tworegions. Then, the display controller 8 causes the display 12 to displaya tomographic image in each of the split regions.

Here, an example of an ultrasound image displayed on the display 12 willbe shown in FIG. 2. FIG. 2 is a view showing an example of a screendisplaying two tomographic images side by side. As shown in FIG. 2, thedisplay controller 8 causes the display 12 to simultaneously display atomographic image 100 and a tomographic image 200 side by side. Forexample, the tomographic image 100 and the tomographic image 200 areimages generated by scanning one cross section of the subject andacquired at different times.

(Contrast Imaging)

Further, a plurality of ultrasound images captured in a state that acontrast agent is injected in the subject may be simultaneouslydisplayed side by side. For example, in a state that a contrast agent isinjected in the subject, the inside of the subject is scanned by theultrasound probe 2 and the transceiver 3. Then, the image generator 6generates harmonic image data based on harmonic components of thereception signals by the Contrast Harmonic Imaging (CHI) method.Besides, the image generator 6 generates body tissue image datarepresenting body tissue based on fundamental components of thereception signals. A harmonic image shows a site in which microbubblesof the contrast agent are injected is enhanced. On the other hand, abody tissue image shows the morphology of each site, the morphology of alesion site such as tumor, or the like. Then, sequential scan of onecross section of the subject is executed by the ultrasound probe 2 andthe transceiver 3, and the image generator 6 sequentially generates thebody tissue image data and the harmonic image data in the cross section.The body tissue image data and the harmonic image data generated by theimage generator 6 are stored into the image storage 7. The displaycontroller 8 receives the body tissue image data and the harmonic imagedata outputted from the image generator 6, and causes the display 12 tosimultaneously display, side by side, a body tissue image based on thebody tissue image data and a harmonic image based on the harmonic imagedata. Moreover, when the operator designates a desired time phase byusing the operation part 13, the display controller 8 reads, from theimage storage 7, the body tissue image data and the harmonic image dataacquired in the designated time phase, and causes the display 12 tosimultaneously display the body tissue image and the harmonic image sideby side. The harmonic image data is equivalent to an example of“contrast-agent image data” of the present invention.

(Measurement Marker)

The display controller 8 causes the display 12 to display a measurementmarker (a measurement caliper) on an ultrasound image. This measurementmarker is used for obtaining quantitative information of tissue shown inan ultrasound image. Plural types of measurement markers are prepareddepending on the intended use of measurement, and data representing ameasurement marker having an initial shape and an initial size ispreviously stored in a setting-information storage 9. For example, ameasurement marker for measuring the distance between two points, ameasurement marker for measuring the perimeter of a site, a measurementmarker for measuring the area of a site, etc. are prepared. Datarepresenting these measurement markers are previously stored in thesetting-information storage 9.

The display controller 8 causes the display 12 to display themeasurement markers in a state superimposed on a plurality of ultrasoundimages in relatively the same positions. By operating the operation part13, the operator can move the measurement marker to a desired positionon the screen of the display 12. For example, when the operator movesthe mouse or the trackball, the display controller 8 receivesinformation representing the movement amount thereof from the operationpart 13 and controls to display the measurement marker in a positionaccording to the movement amount on the screen of the display 12.

Here, as an example, a measurement marker for measuring the distancebetween two points will be described with reference to FIGS. 3 through10. FIGS. 3 through 10 are views showing an example of a screendisplaying the measurement marker on a screen displaying two tomographicimages side by side.

The display controller 8 reads data representing the measurement markerof an initial state from the setting-information storage 9 and controlsto display the measurement marker in an initial position on the screenof the display 12. For example, as shown in FIG. 3, the displaycontroller 8 splits a region on the screen of the display 12 into afirst display region 120 and a second display region 220. Then, thedisplay controller 8 controls to display the tomographic image 100within the first display region 120 and controls to display thetomographic image 200 within the second display region 220.

Besides, the display controller 8 controls to display a firstmeasurement marker 110 in the middle of the first display region 120 fordisplaying the tomographic image 100. The display controller 8 alsocontrols to display a second measurement marker 210 in the middle of thesecond display region 220 for displaying the tomographic image 200. Thefirst display region 120 is a range in which the first measurementmarker 110 can move, and the second display region 220 is a range inwhich the second measurement marker 210 can move. As an example, each ofthe first measurement marker 110 and the second measurement marker 210is composed of a major marker (a major caliper) and a minor marker (aminor caliper), which have cross shapes. The major marker is a markerfor designating the start point of the two points, and the minor markeris a marker for designating the end point.

Then, by using the operation part 13, the operator designates either thefirst measurement marker 110 or the second measurement marker 210 andmoves the designated measurement marker. For example, the operatordesignates the first measurement marker 110 by using the operation part13 and moves the first measurement marker 110. The display controller 8receives information representing the movement amount from the operationpart 13 and controls to display the first measurement marker 110 in aposition according to the movement amount within the first displayregion 120. It is preferred that the display controller 8 causes thedisplay 12 to display a measurement marker designated by the operator soas to be distinguishable from the other measurement marker. For example,it is preferred that the display controller 8 causes the display 12 todisplay a measurement marker designated by the operator with color orsize different from that of the other measurement marker. In the exampleshown in FIG. 3, the display controller 8 can cause the display 12 todisplay the first measurement marker 110 with color or size differentfrom that of the second measurement marker 210.

Consequently, the operator can recognize a measurement marker to beoperated and can recognize an image on which the measurement marker tobe operated is displayed.

Furthermore, the display controller 8 controls to display the secondmeasurement marker 210 in relatively the same position as the firstmeasurement marker 110 within the second display region 220. Forexample, as shown in FIG. 4, the display controller 8 controls todisplay the first measurement marker 110 and the second measurementmarker 210 in relatively the same positions within the first displayregion 120 and the second display region 220, respectively.

For example, with reference to the coordinate system on the screen ofthe display 12, the display controller 8 controls to display the firstmeasurement marker 110 and the second measurement marker 120 inrelatively the same positions within the first display region 120 andthe second display region 220, respectively. That is, the displaycontroller 8 specifies the position of the first measurement marker 110within the first display region 120 and controls to display the secondmeasurement marker 210 in relatively the same position as the specifiedposition, within the second display region 220.

Alternatively, with reference to the coordinate system on the real spacein which the tomographic image 100 and the tomographic image 200 havebeen acquired, the display controller 8 may control to display the firstmeasurement marker 110 and the second measurement marker 210,respectively, in relatively the same positions on the real space withinthe first display region 120 and the second display region 220. That is,the display controller 8 specifies the position on the real space of thefirst measurement marker 110 on the tomographic image I 00 and controlsto display the second measurement marker 210 in a position on thetomographic image 200 corresponding to a position on the real space thatis relatively the same as the position on the real space of the firstmeasurement marker 110.

For example, the display controller 8 specifies the position on the realspace of the first measurement marker 110 in accordance with themovement amount outputted from the operation part 13. Besides, thedisplay controller 8 specifies, in the split region on the screen, aposition corresponding to the position on the real space of the firstmeasurement marker 110 and controls to display the first measurementmarker 110 in the specified position. In other words, the displaycontroller 8 specifies, within the first display region 120, a positioncorresponding to the position on the real space of the first measurementmarker 110 and controls to display the first measurement marker 110 inthe specified position. In addition, the display controller 8 controlsto display, within the second display region 220, the second measurementmarker 210 in a position that is relatively the same as the position onthe real space of the first measurement marker 110.

To be specific, the display controller 8 controls to display the firstmeasurement marker 110 and the second measurement marker 210 on thetomographic image 100 and the tomographic image 200, in equal positions(depths) in the depth direction and equal positions in the scanningdirection.

By thus displaying the measurement markers with reference to thecoordinate system on the real space, even if conditions such as thedepth of transmission of ultrasound waves, the width of scan and themagnification of an image are different among a plurality of ultrasoundimages, it is possible to display the measurement markers in relativelythe same positions on the plurality of ultrasound images. For example,even if the size and magnification of an image, etc. are differentbetween the tomographic image 100 and the tomographic image 200, it ispossible to display the measurement markers in relatively the samepositions on the tomographic image 100 and the tomographic image 200 bydisplaying the measurement markers with reference to the coordinatesystem on the real space.

Then, the operator moves the first measurement marker 110 to a desiredposition by using the operation part 13 and fixes the position of afirst major marker 111 constituting the first measurement marker 110.For example, as shown in FIG. 5, the display controller 8 moves thefirst major marker 111 constituting the first measurement marker 110 tothe designated position in accordance with the movement amount outputtedfrom the operation part 13, and controls to display it on the display12. Then, the display controller 8 fixes the first major marker 111 in aposition of the movement destination in accordance with the instructionfor fixing the position by the operation part 13, and controls todisplay it on the display 12. Besides, the display controller 8 fixes,within the second display region 220, a second major marker 211constituting the second measurement marker 210 in relatively the sameposition as the first major marker 111, and controls to display thesecond major marker 211.

At this point, it is possible to freely move a first minor marker 112constituting the first measurement marker 110 and a second minor marker212 constituting the second measurement marker 210. The operator movesthe first minor marker 112 constituting the first measurement marker 110to a desired position by using the operation part 13. In accordance withthe movement amount outputted from the operation part 13, the displaycontroller 8 moves the first minor marker 112 to a designated positionand controls to display it on the display 12. At this moment, thedisplay controller 8 controls to display the second minor marker 212constituting the second measurement marker 210 in relatively the sameposition as that of the first minor marker 112 within the second displayregion.

Coordinate information representing the position of the first majormarker and coordinate information representing the position of the firstminor marker are outputted from the display controller 8 to themeasuring part 10.

For example, coordinate information representing the position on thereal space of the first major marker and coordinate informationrepresenting the position of the first minor marker are outputted fromthe display controller 8 to the measuring part 10.

(Measuring Part 10)

The measuring part 10 obtains quantitative information of tissuedesignated by the measurement marker. In the case of obtaining thedistance between two points, the measuring part 10 receives, from thedisplay controller 8, coordinate information representing the positionon the real space of the first major marker 111 and coordinateinformation representing the position of the first minor marker 112, andobtains the distance between the first major marker 111 and the firstminor marker 112. For example, the measuring part 10 obtains the lengthof a line between the first major marker 111 and the first minor marker112. Alternatively, the measuring part 10 may obtain the length of acurve between the first major marker 111 and the first minor marker 112.In the case of obtaining the length of the curve, the measuring part 10,for example, sets a spline curve between the first major marker 111 andthe first minor marker 112 and obtains the length of the spline curve.Then, the measuring part 10 outputs the measurement value to the displaycontroller 8. For example, the measuring part 10 outputs, to the displaycontroller 8, information representing the length of a line between thefirst major marker 111 and the first minor marker 112. The displaycontroller 8 receives the measurement value from the measuring part 10and controls to display the measurement value on the display 12. Forexample, as shown in FIG. 5, the display controller 8 controls todisplay the measurement value in a display field A. Since the distancebetween two points is measured as an example, the distance between thefirst major marker 111 and the first minor marker 112 is displayed asthe measurement value (Dist A: 59.2 mm) on the display 12. The measuringpart 10 is equivalent to an example of a “measuring part” of the presentinvention.

Further, by using the operation part 13, the operator can move the firstminor marker 112 and the second minor marker 212 to desired positions.The measuring part 10 receives coordinate information representing themovement destination position of the first minor marker 112 from thedisplay controller 8 and newly obtains the distance between the firstmajor marker 111 and the first minor marker 112. The display controller8 controls to display the newly obtained distance between the two pointson the display 12. Thus, as the first minor marker 112 (the second minormarker 212) is moved, the measuring part 10 newly obtains the distancebetween the first major marker 111 and the first minor marker 112, andthe display controller 8 controls to display the new distance on thedisplay 12.

The second major marker 211 constituting the second measurement marker210 is displayed in the same position on the real space as the firstmajor marker 111. Moreover, the second minor marker 212 constituting thesecond measurement marker 210 is displayed in the same position on thereal space as the first minor marker 112. Consequently, the distancebetween the second major marker and the second minor marker is equal tothe distance between the first major marker and the first minor marker.Therefore, the measuring part 10 can receive, from the displaycontroller 8, either the coordinate information of the first measuringmarker 110 or the coordinate information of the second measuring marker210, thereby obtaining the distance between two points.

Then, the operator fixes the position of the first minor marker 112constituting the first measurement marker 110 by using the operationpart 13.

In accordance with the instruction for fixing the position by theoperation part 13, the display controller 8 fixes the first minor marker112 and the second minor marker 212 in the movement destinationpositions and controls to display on the display 12. Then, the displaycontroller 8 controls to display the measurement value obtained by themeasuring part 10 in a display field B as shown in FIG. 6.

The display controller 8 may generate a linear marker connecting themajor marker and the minor marker and cause the display 12 to displaythe linear marker between the major marker and the minor marker. Forexample, as shown in FIGS. 5 and 6, the display controller 8 controls todisplay a linear marker connecting the first major marker 111 and thefirst minor marker 11 2 between the first major marker 111 and the firstminor marker 112. The display controller 8 also controls to display alinear marker connecting the second major marker 211 and the secondminor marker 212 between the second major marker 211 and the secondminor marker 212.

Alternatively, it is possible to configure to rotate a measurementmarker. When the operator designates a measurement marker and gives aninstruction for rotating by using the operation part 13, the displaycontroller 8, in accordance with the instruction for rotating, rotatesthe measurement marker about a predetermined axis and controls todisplay on the display 12.

For example, the operator designates the first measurement marker 110 byusing the operation part 13, and rotates the first measurement marker110 in the X direction as shown in FIG. 7. In accordance with therotation amount outputted from the operation part 13, the displaycontroller 8 rotates the first measurement marker 110 in the X directionand controls to display on the display 12. At this moment, in accordancewith the rotation amount, the display controller 8 rotates the secondmeasurement marker 210 in the X direction in the same manner as thefirst measurement marker 110 and controls to display on the display 12.When the measurement marker is thus rotated and a new position isdesignated, coordinate information representing the position of thefirst major marker 111 and coordinate information representing theposition of the first minor marker 112 after rotation are outputted tothe measuring part 10. The measuring part 10 obtains the distancebetween the first major marker 111 and the first minor marker 112 afterrotation, and the display controller 8 controls to display the distanceon the display 12.

Further, it is possible to configure so that the position of themeasurement marker can be corrected after the first measurement marker110 and the second measurement marker 210 are fixed and displayed. Inthis case, when the operator instructs correction of the measurementmarker by using the operation part 13, a signal representing theinstruction is outputted to the display controller 8. The displaycontroller 8 receives the instruction and causes the display 12 todisplay a cursor for designating the measurement marker to be corrected.Data representing this cursor is previously stored in thesetting-information storage 9. For example, as shown in FIG. 8, thedisplay controller 8 controls to display a cursor P within an imageregion 300 including the tomographic image 100 and the tomographic image200. The cursor P can be moved within the image region 300.

The operator moves the cursor P by using the operation part 13 anddesignates a marker whose position is to be changed. For example, asshown in FIG. 9, when the operator designates the second minor marker212 with the cursor P by using the the operation part 13, the secondminor marker 212 and the first minor marker 112 corresponding to thesecond minor marker 212 are set into the display controller 8 as movablemarkers. The display controller 8 causes the display 12 to display thesecond minor marker 212 designated with the cursor P so as to bedistinguishable from the other markers. For example, the displaycontroller 8 causes the display 12 to display the second minor marker212 in different color from the other markers. By thus displaying amarker designated with the cursor P so as to be distinguishable from theother markers, it is possible to make the operator grasp a marker thatis a correction target and is movable. Moreover, the display controller8 may cause the display 12 to display the first minor marker 112corresponding to the second minor marker 212 in different color.

Then, as shown in FIG. 10, the operator moves the second minor marker212 (the first minor marker 112) to a desired position by using theoperation part 13. In accordance with the movement amount outputted fromthe operation part 13, the display controller 8 moves the second minormarker 212 to a designated position and controls to display on thedisplay 12. At this moment, the display controller 8 controls to displaythe first minor marker 112 in relatively the same position as the secondminor marker 212, within the first display region. When the position ofthe first measurement marker 110 (the second measurement marker 210) isnewly designated in this manner, coordinate information representing theposition of the first major marker 111 and coordinate informationrepresenting the position of the first minor marker 112 are outputtedfrom the display controller 8 to the measuring part 10. The measuringpart 10 newly obtains the distance between the first major marker 111and the first minor marker 112, and the display controller 8 controls todisplay the distance as the measurement value in the display field A.

(Another Example of Measurement Marker)

Other than a measurement marker for measuring the distance between twopoints, various measurement markers may be used. For example, it ispossible to use a measurement marker having a circular shape, anelliptical shape, a rectangular shape, a mesh shape, a triangular shape,or any curved shape. Measurement markers with initial shapes arepreviously stored in the setting-information storage 9 and, when theoperator selects a desired measurement marker by using the operationpart 13, the display controller 8 causes the display 12 to display theselected measurement marker. Besides, the measurement marker isconfigured so that the operator can arbitrarily change the size thereofother than the position thereof by using the operation part 13. Here, anexample of the measurement marker will be described with reference toFIG. 11. FIG. 11 is a view of a screen showing an example of themeasurement marker.

(Measurement Marker for Obtaining Angle

Fog example, the display controller 8 causes the display 12 to display afirst measurement marker 133 and a second measurement marker 233, whichare two linear markers crossing each other, in a state superimposed onthe tomographic image 100 and the tomographic image 200, respectively.When the operator moves the first measurement marker 133 to a desiredposition on the tomographic image 100 by using the operation part 13,the display controller 8, in accordance with the movement amountoutputted from the operation part 13, moves the first measurement marker133 to a designated position and controls to display on the display 12.The display controller 8 controls to display the second measurementmarker 233 in relatively the same position as the first measurementmarker 133, on the tomographic image 200.

Moreover, when the operator changes the angle formed by the two markerscomposing the first measurement marker 133 by using the operation part13, the display controller 8, in accordance with an angle designated bythe operation part 13, changes the angle formed by the two markerscomposing the first measurement marker 133 and the angle formed by thetwo markers composing the second measurement marker 233, and controls todisplay on the display 12. The measuring part 10 receives coordinateinformation of the two linear markers composing the first measurementmarker 133 from the display controller 8, and obtains an angle at whichthe two linear markers cross each other. The display controller 8 causesthe display 12 to display the angle as the measurement value.

(Circular Measurement Marker)

Further, the display controller 8 may cause the display 12 to display afirst measurement marker 134 and a second measurement marker 234, whichhave circular shapes, on the tomographic image 100 and the tomographicimage 200, respectively. When the operator moves the first measurementmarker 134 to a desired position on the tomographic image by using theoperation part 13, the display controller 8, in accordance with themovement amount outputted from the operation part 13, moves the firstmeasurement marker 134 to the designated position, and controls todisplay on the display 12. At this moment, the display controller 8controls to display the second measurement marker 234 in relatively thesame position as the first measurement marker 134 on the tomographicimage 200. Moreover, when the operator changes the size of the firstmeasurement marker 134 by using the operation part 13, the displaycontroller 8, in accordance with the size designated by the operationpart 13, changes the size of the first measurement marker 134 and thesize of the second measurement marker 234, and controls to display onthe display 12. The measuring part 10 receives coordinate information ofthe first measurement marker 134 from the display controller 8, andobtains the perimeter of a circle indicated by the first measurementmarker 134 and the area of the inside of the circle. The displaycontroller 8 causes the display 12 to display the perimeter and the areaas the measurement values. For example, by surrounding a site to bemeasured with a circular measurement marker, it is possible to obtainthe perimeter and area of the site.

(Measurement Marker Having Arbitrary Shape)

Further, the display controller 8 may cause the display 12 to display afirst measurement marker 135 and a second measurement marker 235, whichsurround desired ranges and have arbitrary shapes, on the tomographicimage 100 and the tomographic image 200, respectively. For example, whenthe operator designates an arbitrary shape surrounding a desired rangeon the tomographic image 100 by using the operation part 13, the displaycontroller 8 causes the display 12 to display the first measurementmarker 135 having a shape designated by the operation part 13, on thetomographic image 100.

Moreover, the display controller 8 controls to display, on thetomographic image 200, the second measurement marker 235 having the sameshape as the shape of the first measurement marker 135 in relatively thesame position as the first measurement marker 135. The measuring part 10receives coordinate information of the first measurement marker 135 fromthe display controller 8, and obtains the perimeter of the shapeindicated by the first measurement marker 135 and the area of the insideof the shape. The display controller 8 causes the display 12 to displaythe perimeter and the area as the measurement values. By thus using ameasurement marker having an arbitrary shape, it is possible todesignate a desired range on a tomographic image and obtain theperimeter and area of the range. For example, by surrounding a site tobe measured having a complicated shape with this measurement marker, itis possible to obtain the perimeter and area of the site.

Further, in a case that the distance between two points is to beobtained by using a first measurement marker 131 (a second measurementmarker 231) having a major marker and a minor marker, the measuring part10 may set a spline curve between the two points and obtain the lengthof the spline curve. Moreover, also in a case that the distance betweentwo points composing a first measurement marker 132 (a secondmeasurement marker 232) is to be obtained, the measuring part 10 may setanother spline curve between the two points and obtain the length of thespline curve. In a case that a spline curve is thus set, the displaycontroller 8 controls to display a marker representing the shape of thespline curve between the major marker and the minor marker.

(Superimposed Image of B-Mode Image and Color Doppler Image)

Further, a measurement marker may be displayed on a superimposed imagein which a B-mode image obtained by imaging in the B-mode and a colorDoppler image obtained by imaging in the color Doppler mode aresuperimposed on each other. An example of a superimposed image on whichthe measurement marker is superimposed is shown in FIG. 12. FIG. 12 is aview showing an example of a screen displaying a measurement marker on ascreen displaying a tomographic image and a superimposed image side byside. The display controller 8 causes the display 12 to display atomographic image 400 obtained by imaging in the B-mode. Moreover, thedisplay controller 8 causes the display 12 to display a superimposedimage in which a tomographic image 410 obtained by imaging in the B-modeand a color Doppler image 430 obtained by imaging in the color Dopplermode. Then, as in the aforementioned process, the display controller 8causes the display 12 to display the first measurement marker 110 in astate superimposed on the tomographic image 400 and display the secondmeasurement marker 210 in relatively the same position as the firstmeasurement marker 110 on the superimposed image. Also in this case, themeasuring part 10 obtains the distance between two points designated bythe first measurement marker 110, and the display controller 8 controlsto display the distance as the measurement value in the display field B.

(Display of Measurement Marker on Reversed Image)

Further, one of the two ultrasound images displayed on the display 12may be reversed horizontally or vertically to be displayed. In thiscase, the display controller 8 controls to display the measurementmarkers in relatively the same positions on the two ultrasound images,respectively, with reference to the coordinate system on the real space.A vertically reversed ultrasound image is shown in FIG. 13. FIG. 13 is aview showing an example of a screen displaying a measurement marker onthe vertically reversed tomographic image.

As shown in FIG. 13, the display controller 8 causes the display 12 tosimultaneously display a tomographic image 500 and a tomographic image520 side by side. Here, the display controller 8 vertically reverses thetomographic image 500 with respect to the tomographic image 520, andcauses the display 12 to display the tomographic image 500 and thetomographic image 520. On the screen of the display 12, the upperportion of the tomographic image 520 is shallower, and the lower portionof the tomographic image 520 is deeper. On the other hand, the upperportion of the tomographic image 500 is deeper, and the lower portionthereof is shallower.

In this case, the display controller 8 controls to display themeasurement markers in relatively the same positions on the real spaceon the tomographic image 500 and the tomographic image 520. For example,the operator designates, by using the operation part 13, the positionsof a first major marker 511 and a first minor marker 512 composing afirst measurement marker 510. The display controller 8 controls todisplay the first major marker 511 and the first minor marker 512 in thepositions designated with the operation part 13 on the tomographic image500. Moreover, the display controller 8 specifies the position on thereal space of the first measurement marker 510 on the tomographic image500. Then, the display controller 8 controls to display a secondmeasurement marker 530 in a position on the tomographic image 520corresponding to relatively the same position on the real space as theposition on the real space of the first measurement marker 510.

To be specific, the display controller 8 controls to display a secondmajor marker 531 in a position on the tomographic image 520corresponding to the same depth on the real space as the depth of thefirst major marker 511 shown on the tomographic image 500. Moreover, thedisplay controller 8 controls to display the second major marker 531 ina position on the tomographic image 520 corresponding to the sameposition in the scanning direction on the real space as the position inthe scanning direction of the first major marker 511 shown on thetomographic image 500. Similarly, the display controller 8 controls todisplay a first minor marker 512 and a second minor marker 532 in thesame positions on the real space on the tomographic image 500 and thetomographic image 520.

Then, the measuring part 10 receives coordinate information representingthe position on the real space of the first measurement marker 510 fromthe display controller 8, and obtains the distance between the firstmajor marker 511 and the first minor marker 512 as the measurementvalue.

The display controller 8 controls to display the measurement value inthe display field B of the display 12.

Further, for a horizontally reversed ultrasound image, it is possible toobtain quantitative information in the same manner as for the verticallyreversed ultrasound image. The horizontally reversed ultrasound image isshown in FIG. 14. FIG. 14 is a view showing an example of a screendisplaying a measurement marker on the horizontally reversed tomographicimage.

As shown in FIG. 14, the display controller 8 controls to simultaneouslydisplay a tomographic image 600 and a tomographic image 620 side by sideon the display 12. For example, the display controller 8 horizontallyreverses the tomographic image 600 with respect to the tomographic image620, and controls to display the tomographic image 600 and thetomographic image 620 on the display 12.

Also in this case, the display controller 8 controls to displaymeasurement markers in relatively the same positions on the real spaceon the tomographic image 600 and the tomographic image 620. For example,the operator designates, by using the operation part 13, the positionsof a first major marker 611 and a first minor marker 612 composing afirst measurement marker 610. The display controller 8 controls todisplay the first major marker 611 and the first minor marker 612 in thepositions designated with the operation part 13 on the tomographic image600. Moreover, the display controller 8 specifies the position on thereal space of the first measurement marker 610 on the tomographic image600. Then, the display controller 8 controls to display a secondmeasurement marker 630 in a position on the tomographic image 620corresponding to relatively the same position on the real space as theposition of the first measurement marker 610 on the real space.Consequently, a second major marker 631 is displayed in the sameposition as the position on the real space of the first major marker611, on the tomographic image 620. Similarly, a second minor marker 632is displayed in the same position as the position on the real space ofthe first minor marker 612, on the tomographic image 620.

Then, the measuring part 10 receives coordinate information representingthe position on the real space of the first measurement marker 610 fromthe display controller 8, and obtains the distance between the firstmajor marker 611 and the first minor marker 612 as the measurementvalue.

The display controller 8 controls to display the measurement value inthe display field B of the display 12.

Thus, the ultrasound imaging apparatus 1 according to the presentembodiment simultaneously displays a plurality of ultrasound images sideby side and displays measurement markers in relatively the samepositions on the plurality of ultrasound images, respectively, on theimages, whereby the operator can easily specify the positionscorresponding to each other on the plurality of images. Consequently, itbecomes possible to measure a measurement target in each of thecorresponding positions on the plurality of ultrasound images. Forexample, the ultrasound imaging apparatus simultaneously displays a bodytissue image and a harmonic image side by side, and displays measurementmarkers in relatively the same positions on the respective images,whereby the operator can easily grasp the positional relation between alesion part such as tumor and a contrast site. Then, it becomes possibleto obtain quantitative information of tissue in relatively the samepositions on the body tissue image and the harmonic image.

(Image Processor 14)

Next, the image processor 14 will be described. The image processor 14includes a reference-image generator 15 and a tracking part 16. Theimage processor 14 executes pattern matching on a plurality ofultrasound image data acquired at different times, thereby obtaining theposition of tissue of a specified range including a position where themeasurement marker is superimposed, in each of the plurality of imagedata. Thus, the image processor 14 tracks at times the position of themeasurement marker designated on a certain ultrasound image. The imageprocessor 14 is equivalent to an “image processor” of the presentinvention. The ultrasound imaging apparatus 1 may be configured not toinclude the image processor 14.

In the case of tracking the position of the measurement marker, theultrasound imaging apparatus 1 can include the image processor 14. Thereference-image generator 15 and the tracking part 16 will be describedbelow.

(Reference-Image Generator 15)

The reference-image generator 15 receives coordinate informationrepresenting the position of a measurement marker on an ultrasound imagefrom the display controller 8. Moreover, the reference-image generator15 reads ultrasound image data acquired at each time from the imagestorage 7.

Then, the reference-image generator 15 generates image data representingtissue of a specified range including the position of the measurementmarker as reference-image data, based on ultrasound image data in whichthe measurement marker is set. For example, the reference-imagegenerator 15 sets a rectangularly-shaped range including the position ofthe measurement marker and having a specified size, and generatesreference-image data representing tissue in the rectangularly-shapedrange from the ultrasound image data in which the measurement marker isset.

(Tracking Part 16)

The tracking part 16 executes pattern matching on the reference-imagedata and the ultrasound image data acquired at each time, therebyspecifying the position of the tissue of the specified range representedin the reference-image data, in each of the plurality of ultrasoundimage data. By specifying the position of the tissue of the specifiedrange in this manner, the tracking part 16 specifies the position of themeasurement marker in each of the plurality of ultrasound image data.Thus, the tracking part 16 tracks the position of the measurement markerat times. As the pattern matching, for example, the template matchingmethod (the block matching method) can be used. To be specific, thetracking part 16 obtains a subtraction between a reference image and anultrasound image, and obtains a position with the least subtraction,thereby tracking the position of the measurement marker.

The tracking part 16 outputs coordinate information representing theposition of the measurement marker at each time to the displaycontroller 8.

The display controller 8 reads ultrasound image data acquired at eachtime from the image storage 7, and causes the display 12 to display themeasurement marker at each time in a state superimposed on theultrasound image acquired at each time.

By tracking the position of the measurement marker as described above,even if a measurement target is moved and the position thereof ischanged by breathing or beating of a patient, the measurement markerdesignated by the operator automatically follows the measurement targetand keeps designating the measurement target.

As an example, a case of simultaneously displaying a body tissue imagegenerated based on fundamental waves and a harmonic image generatedbased on harmonic waves side by side and setting measurement markers onboth the images will be described with reference to FIGS. 15 and 16.FIGS. 15 and 16 are views showing an example of a screen displaying themeasurement markers on a screen displaying the body tissue image and theharmonic image side by side.

As shown in FIG. 15, the display controller 8 controls to simultaneouslydisplay a body tissue image 710 based on fundamental waves and aharmonic image 700 based on harmonic waves side by side on the display12. A tumor 711 is shown on the body tissue image 710, and a tumor 701is shown on the harmonic image 700. As described above, the operatormoves the measurement marker to a desired position by using theoperation part 13. As an example, a circularly-shaped measurement markeris used. The display controller 8 causes the display 12 to display acircularly-shaped first measurement marker 712 on the body tissue image710. As described above, the display controller 8 controls to displaythe first measurement marker 712 and a second measurement marker 702 inrelatively the same positions on the body tissue image 710 and theharmonic image 700. The operator moves the first measurement marker 712to a desired position by using the operations part 13, and changes thesize of the marker to an arbitrary size. For example, by using theoperation part 13, the operator moves the first measurement marker 712to the position of the tumor 711, changes the size of the firstmeasurement marker 712, and surrounds the tumor 711 by the firstmeasurement marker 712. The display controller 8 causes the display 12to display the first measurement marker 712 surrounding the tumor 711 inaccordance with the movement amount outputted from the operation part13.

Moreover, the display controller 8 controls to display the secondmeasurement marker 702 in relatively the same position as the firstmeasurement maker 712.

As described above, when the position of a tumor is designated by thefirst measurement maker 712, coordinate information representing theposition of the first measurement marker 712 on the body tissue image710 is outputted to the reference-image generator 15. Thereference-image generator 15 generates reference-image data representingtissue of a specified range including the position of the firstmeasurement marker 712, based on body tissue image data in which thefirst measurement marker 712 is set. A body tissue image has highervisibility than a harmonic image, and shows little change in image evenif a contrast agent flows in. Before a contrast agent is injected intothe subject, the morphology of tissue is not shown in a harmonic image.Accordingly, a body tissue image is more suitable for pattern matchingthan a harmonic image, and therefore, reference-image data is generatedfrom body tissue image data.

The tracking part 16 reads the body tissue image data acquired at eachtime, from the image storage 7. Then, the tracking part 16 executespattern matching on the reference-image data and the body tissue imagedata acquired at each time, thereby specifying the position of tissue ofa specified range represented in the reference-image data, in the bodytissue image data at each time. Thus, by specifying the position oftissue of a specified range, the tracking part 16 specifies the positionof the first measurement marker 712 in each of a plurality of bodytissue image data.

The tracking part 16 outputs coordinate information representing theposition of the first measurement marker 712 at each time to the displaycontroller 8. The display controller 8 reads the body tissue image dataand the harmonic image data that have been acquired at each time, fromthe image storage 7. The display controller 8 causes the display 12 tosimultaneously display a body tissue image and a harmonic image thathave been acquired at equal times side by side. Then, in accordance withthe order of acquisition times, the display controller 8 updates thebody tissue image and the harmonic image that have been acquired at eachtime, and causes the display 12 to display. At this moment, the displaycontroller 8 causes the display 12 to display the first measurementmarker 712 at each time obtained by the tracking part 16 on the bodytissue image 710 acquired at each time. Besides, the display controller8 controls to display the second measurement marker 702 in relativelythe same position as the first measurement marker 712 on the harmonicimage 700 acquired at each time. Additionally, the display controller 8controls to display the second measurement marker 702 in relatively thesame position as the first measurement marker 712 on the harmonic image700 acquired at each time.

By thus tracking the position of the measurement marker, it is possibleto specify the position of the tumor shown in the body tissue image andthe position of the contrast agent shown in the harmonic image at eachtime.

Consequently, the operator can easily grasp the positional relationbetween the tumor and the contrast agent.

Furthermore, the measuring part 10 receives coordinate information ofthe first measurement marker 712 at each time from the displaycontroller 8, and obtains the perimeter and area of the measurementtarget indicated by the first measurement marker 712 at each time. Then,the display controller 8 causes the display 12 to display the perimeterand area of the measurement target at each time. By thus tracking themeasurement marker by the tracking part 16, it becomes possible toobtain quantitative information of the measurement target at each time.

Further, as in the harmonic image 700 shown in FIG. 16, when thecontrast agent injected into the subject flows into the vessels, avessel 703 in which the contrast agent flows is enhanced and displayed.In the prior art, it is difficult to grasp the positional relationbetween the tumor 711 shown in the body tissue image 710 and the vessel703 (the vessel 703 enhanced by the contrast agent) shown in theharmonic image 700. In other words, in the conventional art, themeasurement calipers are not displayed in relatively the same positionson the body tissue image 710 and the harmonic image 700, so that it isdifficult to grasp the positional relation between the tumor 711 and thevessel 703.

On the contrary, in this embodiment, the display controller 8 controlsto display the first measurement marker 712 and the second measurementmarker 702 in relatively the same positions on the body tissue image 710and the harmonic image 700. Consequently, it becomes possible to easilygrasp the positional relation between the tumor 711 shown in the bodytissue image 710 and the vessel 703 (the vessel 703 enhanced by thecontrast agent) shown in the harmonic image 700.

(Mesh Measurement Marker)

Further, a mesh measurement marker covering the whole region of eachultrasound image may be displayed. This measurement marker is shown inFIG. 17. FIG. 17 is an example of a screen displaying the measurementmarker on a screen displaying two tomographic images side by side.

For example, the display controller 8 causes the display 12 tosimultaneously display the body tissue image 710 based on fundamentalwaves and the harmonic image 700 based on harmonic waves side by side.

Then, the display controller 8 causes the display 12 to display a firstmesh measurement marker 714 covering the whole region of the body tissueimage 710 on the body tissue image 710. Similarly, the displaycontroller 8 causes the display 12 to display a second mesh measurementmarker 704 covering the whole region of the harmonic image 700 on theharmonic image 700 on the display 12. At this moment, the displaycontroller 8 controls to display the position of each of lines formingthe mesh of the measurement marker in relatively the same positions onthe body tissue image 710 and the harmonic image 700. To be specific,the display controller 8 controls to display the mesh of the firstmeasurement marker 714 on the body tissue image 710 and the mesh of thesecond measurement marker 704 on the harmonic image 700 in relativelythe same positions on the real space, with reference to coordinatesystem on the real space. For example, the display controller 8 controlsto display the mesh of the first measurement marker 714 and the mesh ofthe second measurement marker 704 in the same positions in depth andscanning direction.

As described above, mesh measurement markers covering the whole regionsof images are displayed on the body tissue image 710 and the harmonicimage 700, and further, the meshes are displayed in relatively the samepositions on the body tissue image 710 and the harmonic image 700,whereby the operator can easily grasp the positional relation of a tumorand a contrast agent with reference to the mesh.

Further, in the case of simultaneous display of a harmonic image and abody tissue image, if the position of the subject or the ultrasoundprobe 2 is displaced, scan with ultrasound waves will be executed in thedisplaced position. Consequently, in the harmonic image and the bodytissue image, images of sites in the displaced positions are shown.Therefore, a measurement marker set on each of the harmonic image andthe body tissue image will be set in a position displaced from aninitially set position (a desired measurement target) on each of theimages. As a result, it becomes difficult to keep designating thedesired measurement target with the measurement marker.

Accordingly, in this embodiment, the display position of the harmonicimage on the display 12 is corrected depending on the displacementamount, and the displacement amount is offset to display the harmonicimage, whereby the site shown in the harmonic image is displayed in afixed position on the display 12. Consequently, even if the position ofthe subject or the ultrasound probe 2 is displaced, a state in which themeasurement marker is set in the initially set position (the desiredmeasurement target) is maintained.

On the other hand, since the image of the site in the displaced positionis shown in the body tissue image, the measurement marker remains set inthe position displaced from the initially set position (the desiredmeasurement target).

Accordingly, in this embodiment, the display position of the measurementmarker set on the body tissue image is corrected depending on thedisplacement amount, and the displacement amount is offset to displaythe measurement marker on the body tissue image (a first correctionmethod).

Although the image of the site in the displaced position is shown in thebody tissue image, the measurement marker is displayed in the displayposition corrected depending on the displacement amount, so that a statein which the measurement marker is set in the initially set position(the desired measurement target) is maintained on the body tissue image.

Alternatively, as in the case of the harmonic image, the displayposition of the body tissue image on the display 12 is correcteddepending on the displacement amount and the displacement amount isoffset to display the body tissue image (a second correction method).Consequently, since the site shown in the body tissue image is displayedin a fixed display position on the display 12, a state in which themeasurement marker is set in the initially set position (the desiredmeasurement target) is maintained on the body tissue image.

A specific example of correction of the displacement amount will bedescribed below with reference to FIGS. 18 and 19. FIGS. 18 and 19 areviews showing an example of a screen displaying a measurement marker ona screen displaying a body tissue image and a harmonic image side byside.

(First Correction Method)

First, the aforementioned first correction method will be described withreference to FIG. 18.

As shown in FIG. 18, the display controller 8 causes the display 12 tosimultaneously display the body tissue image 710 based on fundamentalwaves and the harmonic image based on harmonic waves side by side. Thetumor 711 is shown in the body tissue image 710. As an example, thedisplay controller 8 causes the display 12 to display the first circularmeasurement marker 712 (a marker indicated by a broken line) in a statesuperimposed on the body tissue image 710 and display the secondcircular measurement marker 702 in a state superimposed on the harmonicimage 700. When a contrast agent injected into the subject flows in, thevessel 703 in which the contrast agent flows is enhanced and displayedon the harmonic image 700.

The display controller 8 controls to display the first measurementmarker 712 and the second measurement marker 702 in relatively the samepositions on the body tissue image 710 and the harmonic image 700. Forexample, in response to an operator's instruction, the displaycontroller 8 causes the display 12 to display the first measurementmarker 712 surrounding the tumor 711 on the body tissue image 710.Moreover, the display controller 8 causes the display 12 to display thesecond measurement marker 702 on the harmonic image 700, in relativelythe same position as the first measurement marker 712.

The image processor 14 reads harmonic image data acquired at each timefrom the image storage 7. Then, the image processor 14 executes patternmatching on the harmonic image data acquired at each time, therebyspecifying the position of the vessel 703 at each time. That is to say,the image processor 14 sets the vessel 703 represented in the harmonicimage data acquired at each time as a tracking target to track theposition of the vessel 703 at each time by the pattern matching. Theimage processor 14 tracks the position of the vessel 703 represented inthe harmonic image data, thereby detecting the position displacement(the direction and amount of the position displacement) of the vessel703 represented in the harmonic image data, and outputting positiondisplacement information (vector information) representing the directionand the amount of the position displacement to the display controller 8.For example, in a case that the position of the vessel 703 representedin the harmonic image data is displaced as a result of displacement ofthe position of a region scanned with ultrasound waves due to themovement of the subject, the image processor 14 tracks the position ofthe vessel 703 represented in the harmonic image data, thereby detectingthe displacement of the position. As a method of detecting positiondisplacement, for example, the method described in Japanese UnexaminedPatent Publication No. 2007-330764 can be employed.

When receiving the position displacement information (vectorinformation) from the image processor 14, the display controller 8corrects the display position of the harmonic image 700 in accordancewith the position displacement information, and controls to display onthe display 12.

To be specific, the display controller 8 controls to display theharmonic image 700 in a display position displaced by the same distanceas the displacement amount in the direction opposite to the positiondisplacement direction. Consequently, the position displacement isoffset, and a site shown in the harmonic image 700 can be displayed in afixed display position on the display 12. In this state, the displaycontroller 8 fixes the display position, and causes the display 12 todisplay the second measurement marker 702 on the harmonic image 700.Consequently, the second measurement marker 702 will keep designatingthe initially set position (the desired measurement target) on theharmonic image 700.

Further, the display controller 8 corrects the display position of thefirst measurement marker 712 (the marker indicated by the broken line)on the body tissue image 710 in accordance with the positiondisplacement information, and controls to display on the display 12. Tobe specific, the display controller 8 controls to display the firstmeasurement marker in a display position displaced by the same distanceas the displacement amount in the same direction as the positiondisplacement direction represented by the position displacementinformation on the body tissue image 710. In the example shown in FIG.18, the display controller 8 controls to display a post-correction firstmeasurement marker 712A in a display position where the pre-correctionfirst measurement marker 712 (the marker indicated by the broken line)is displaced by the same distance as the displacement amount representedby the position displacement information in an arrow X direction (thesame direction as the position displacement direction). Consequently,the post-correction first measurement marker 712A will keep designatingthe initially set position (the desired measurement target) on the bodytissue image 710.

By the correction process described above, even if the position of thesubject or the ultrasound probe 2 is displaced, it is possible todisplay the measurement markers in relatively the same positions on thebody tissue image 710 and the harmonic image 700.

(Second Correction Method)

Next, the aforementioned second correction method will be described withreference to FIG. 19.

As shown in FIG. 19, the display controller 8 causes the display 12 todisplay the body tissue image 710 based on fundamental waves (an imageframed by a broken line) and the harmonic image 700 based on harmonicwaves side by side. The tumor 711 is shown in the body tissue image 710.As described above, the display controller 8 causes the display 12 todisplay the first measurement marker 712 surrounding the tumor 711 onthe body tissue image 710 (the image framed by the broken line), andcauses the display 12 to display the second measurement marker 702 onthe harmonic image 700, in relatively the same position as the firstmeasurement marker 712.

As in the aforementioned first correction method, the image processor 14reads harmonic image data acquired at each time from the image storage7.

Then, the image processor 14 executes pattern matching on the harmonicimage data acquired at each time, thereby specifying the position of thevessel 703 at each time. That is to say, the image processor 14 sets thevessel 703 represented in the harmonic image data acquired at each timeas a tracking target, and tracks the position of the vessel 703 at eachtime by the pattern matching. The image processor 14 tracks the positionof the vessel 703 represented in the harmonic image data, therebydetecting the position displacement (the direction and amount of theposition displacement) of the vessel 703 represented in the harmonicimage data, and outputting position displacement information (vectorinformation) representing the direction and the amount of the positiondisplacement to the display controller 8.

When receiving the position displacement information (vectorinformation) from the image processor 14, as in the aforementioned firstcorrection method, the display controller 8 controls to display theharmonic image 700 in a display position displaced by the same distanceas the displacement amount in the direction opposite to the positiondisplacement direction. Consequently, the position displacement isoffset, and a site shown in the harmonic image 700 can be displayed in afixed display position on the display 12. In this state, the displaycontroller 8 fixes the display position, and causes the display 12 todisplay the second measurement marker 702 in a state superimposed on theharmonic image 700. Consequently, the second measurement marker 702 willkeep designating the initially set position (the desired measurementtarget) on the harmonic image 700.

Further, the display controller 8 corrects the display position of thebody tissue image 710 (the image framed by the broken line) inaccordance with the position displacement information, and controls todisplay on the display 12. To be specific, the display controller 8controls to display the body tissue image in a display positiondisplaced by the same distance as the displacement amount in theopposite direction to the position displacement direction represented bythe position displacement information. In the example shown in FIG. 19,the display controller 8 controls to display a post-correction bodytissue image 710A in a display position where the pre-correction bodytissue image 710 (the image framed by the broken line) is displaced bythe same distance as the displacement amount represented by the positiondisplacement information in an arrow Y direction (the opposite directionto the position displacement direction). In this state, the displaycontroller 8 fixes the display position, and causes the display 12 todisplay the first measurement marker 712 in a state superimposed on thebody tissue image 710A. Consequently, the first measurement marker 712will keep designating the initially set position (the desiredmeasurement target) on the post-correction body tissue image 710A.

By the correction process described above, even if the position of thesubject or the ultrasound probe 2 is displaced, it is possible todisplay the measurement markers in relatively the same positions on thebody tissue image 710 and the harmonic image 700.

(Display of Previous Image)

The display controller 8 may attach identification informationrepresenting simultaneous display to a plurality of ultrasound imagedata simultaneously displayed side by side on the display 12 and causethe image storage 7 to store as previous image data. In the case ofcausing the display 12 to simultaneously display, side by side, aplurality of previous images based on the previous image data with theidentification information attached, the display controller 8 causes thedisplay 12 to display measurement markers in relatively the samepositions on the respective previous images. Thus, in the case ofsimultaneously displaying a plurality of previous images side by side,it is also possible to display the measurement markers in relatively thesame positions and obtain quantitative information in correspondingpositions.

The display controller 8 may cause the display 12 to display previousimages side by side, or may cause the display 12 to display a previousimage and an ultrasound image acquired in real time side by side. In thecase of simultaneously displaying a plurality of previous images side byside, it is preferred that the display controller 8 causes the display12 to display a measurement marker to be operated by the operator so asto be distinguishable from other measurement markers. For example, it ispreferred that the display controller 8 causes the display 12 to displaythe measurement marker to be operated in color and size different fromthose of other measurement markers. Moreover, in the case ofsimultaneously displaying a previous image and an ultrasound imageacquired in real time side by side, it is preferred to cause the display12 to display a measurement marker displayed on the previous image orthe real-time image so as to be distinguishable from other measurementmarkers. Consequently, the operator can differentiate and recognize theprevious image and the real-time image from among the plurality ofimages displayed on the display 12.

Each of the image generator 6, the display controller 8, the measuringpart 10 and the image processor 14 may be composed of a not-shown CPU(Central Processing Unit) and a not-shown storage device such as a ROM(Read Only Memory), a RAM (Random Access Memory) and an HDD (Hard DiskDrive). The storage device stores an image generation program forexecuting the function of the image generator 6, a display controlprogram for executing the function of the display controller 8, ameasurement program for executing the function of the measuring part 10,and an image processing program for executing the function of the imageprocessor 14. Moreover, the image processing program includes areference-image generation program for executing the function of thereference-image generator 15, and a tracking program for executing thefunction of the tracking part 16.

By execution of the image generation program, the CPU generatesultrasound image data such as tomographic image data based on signalsacquired in transmission/reception of ultrasound waves. Moreover, byexecution of a marker generation program, the CPU generates datarepresenting the measurement marker. Moreover, by execution of thedisplay control program, the CPU causes the display 12 to display anultrasound image based on ultrasound image data, and further, controlsto display the measurement marker in a state superimposed on theultrasound image.

Moreover, by execution of the reference-image generation program, theCPU generates reference-image data representing a specified rangeincluding a position on which the measurement marker is superimposed.

Moreover, by execution of the tracking program, the CPU specifies theposition of the measurement marker in each of the plurality ofultrasound image data.

(Medical Image processing Apparatus)

Further, a medical image processing apparatus that simultaneouslydisplays a plurality of ultrasound images side by side may be disposedoutside the ultrasound imaging apparatus. This medical image processingapparatus includes the aforementioned image storage 7, displaycontroller 8, user interface (UI) 11, measuring part 10, and imageprocessor 14. In a case that tracking of the measurement marker is notexecuted, the image processor 14 may be eliminated from the medicalimage processing apparatus. The medical image processing apparatusacquires a plurality of ultrasound image data from the externalultrasound imaging apparatus, simultaneously displays a plurality ofultrasound images side by side, and displays measurement markers inrelatively the same positions on the respective ultrasound images.

This medical image processing apparatus can also produce the sameactions and effects as the aforementioned ultrasound imaging apparatus1.

What is claimed is:
 1. An ultrasound imaging apparatus, comprising: animaging part configured to acquire a plurality of sets of ultrasoundimage data by sequentially imaging a subject with ultrasound waves at acorresponding plurality of different times; and a display controllerconfigured to cause a display to display, side by side in respectivedisplay regions, a plurality of ultrasound images based on the pluralityof sets of ultrasound image data acquired by the imaging part at thecorresponding plurality of different times, and cause the display todisplay markers in a state superimposed on the plurality of ultrasoundimages, respectively, in the same corresponding positions in each of theultrasound images with respect to a coordinate system in a real space inwhich the plurality of sets of ultrasound image data were acquired, evenif the display magnification rate of the plurality of ultrasound imagesis different.
 2. The ultrasound imaging apparatus according to claim 1,further comprising: an image storage configured to attach, to theplurality of sets of ultrasound image data representing the plurality ofultrasound images displayed side by side on the display, identificationinformation representing the display side by side, and store theplurality of sets of ultrasound image data as previous ultrasound imagedata, wherein the display controller is configured to cause the displayto display a plurality of sets of previous ultrasound images based onthe plurality of previous ultrasound image data, and to cause thedisplay to display the markers in a state superimposed on the respectiveprevious ultrasound images in the same corresponding positions in eachof the previous ultrasound images.
 3. The ultrasound imaging apparatusaccording to claim 1, wherein: the apparatus further includes an imageprocessor configured to obtain, as reference-image data, image datarepresenting tissue of a specified range including a position where themarker is superimposed and to execute pattern matching on thereference-image data and the plurality of sets of ultrasound image datasequentially acquired, thereby specifying a position of the tissue ofthe specified range represented in the reference-image data in each ofthe plurality of sets of ultrasound image data, and specifying theposition where the marker is superimposed on the plurality of ultrasoundimages from the specification; and the display controller, in accordancewith the positions of the markers specified by the image processor, isconfigured to cause the display to display the markers in a statesuperimposed on the plurality of ultrasound images, respectively, in thesame corresponding positions in each of the ultrasound images.
 4. Theultrasound imaging apparatus according to claim 1, further comprising:an operation part configured to designate the marker displayed in asuperimposed state on one of the plurality of ultrasound imagesdisplayed on the display, and to move the designated marker to a desiredposition on the one ultrasound image, wherein: the display controller isconfigured to specify a position in the real space of the desiredposition on the one ultrasound image, and to cause the display todisplay the markers in a state superimposed on the ultrasound imagesother than the one ultrasound image, in positions on the imagescorresponding to positions that are the same as the specified positionin the real space.
 5. The ultrasound imaging apparatus according toclaim 1, wherein: the display controller causes the display to display,as the marker, a marker having a circular, elliptic, rectangular,mesh-shaped, triangular, or arbitrary curved shape.
 6. The ultrasoundimaging apparatus according to claim 1, wherein: the display controlleris configured to display a mesh marker having lines like a mesh, and tocause the display to display the mesh marker so that positions of therespective lines forming the mesh of the mesh marker are superimposed onthe plurality of ultrasound images, respectively, in the samecorresponding positions in each of the ultrasound images.
 7. Theultrasound imaging apparatus according to claim 1, further comprising: ameasuring part configured to obtain quantitative information of thetissue shown in the plurality of ultrasound images in the positiondesignated by the markers.
 8. A method for displaying an ultrasoundimage, comprising: acquiring a plurality of sets of ultrasound imagedata by sequentially imaging a subject with ultrasound waves at acorresponding plurality of different times; and displaying, side by sidein respective display regions, a plurality of ultrasound images based onthe plurality of sets of acquired ultrasound image data acquired at thecorresponding plurality of different times, and displaying markers in astate superimposed on the plurality of ultrasound images, respectively,in the same corresponding positions in each of the ultrasound imageswith respect to a coordinate system in a real space in which theplurality of sets of ultrasound image data were acquired, even if thedisplay magnification rate of the plurality of ultrasound images isdifferent.
 9. The method for displaying an ultrasound image according toclaim 8, further comprising: attaching to the plurality of sets ofultrasound image data representing the plurality of ultrasound imagesdisplayed side by side, identification information representing thedisplay side by side, and storing the plurality of sets of ultrasoundimage data as previous ultrasound image data into an image storage,wherein the displaying step includes displaying a plurality of previousultrasound images based on the plurality of previous ultrasound imagedata, and displaying the markers in a state superimposed on therespective previous ultrasound images in the same correspondingpositions in each of the previous ultrasound images.
 10. The method fordisplaying an ultrasound image according to claim 8, further comprising:obtaining image data representing tissue of a specified range includinga position where the marker is superimposed as reference-image data, andexecuting pattern matching on the reference-image data and the pluralityof sets of sequentially acquired ultrasound image data, whereby aposition of the tissue of the specified range represented in thereference-image data is specified in each of the plurality of sets ofultrasound image data, and the position where the marker is superimposedis specified in each of the plurality of ultrasound image from thespecification, wherein the displaying step includes displaying, inaccordance with the specified positions of the markers, the markers in astate superimposed on the respective ultrasound images in the samecorresponding positions in each of the ultrasound images.
 11. The methodfor displaying an ultrasound image according to claim 8, furthercomprising: designating the marker displayed in a superimposed state onone of the plurality of displayed ultrasound images, and moving thedesignated marker to a desired position on the one ultrasound image,wherein the displaying step includes specifying a position in the realspace of the desired position on the one ultrasound image, anddisplaying the markers in a state superimposed on the ultrasound imagesother than the one ultrasound image, in positions on the imagescorresponding to positions that are the same as the specified positionin the real space.
 12. The method for displaying an ultrasound imageaccording to claim 8, wherein the displaying step comprises: displayinga marker having a circular, elliptic, rectangular, mesh-shape,triangular, or arbitrary curved shape as the marker.
 13. The method fordisplaying an ultrasound image according to claim 8, wherein thedisplaying step comprises: displaying a mesh marker having lines like amesh as the marker, and superimposing positions of the respective linesforming the mesh of the mesh marker on the plurality of ultrasoundimages, respectively, in the same corresponding positions in each of theultrasound images.
 14. The method for displaying an ultrasound imageaccording to claim 8, further comprising: obtaining quantitativeinformation of the tissue shown in the plurality of ultrasound images inthe position designated by the markers.